Depression for ethnic minorities is a common, disabling condition with documented disparities in access, quality and outcomes of care, particularly in primary care, which is a main treatment setting for ethnic minority groups. Quality improvement programs in primary care can reduce disparities in depression outcomes but are seldom available in vulnerable communities. The proposed project will use the data, partnership infrastructure, and research approach of Community Partners in Care (CPIC)-augmented by new collection of qualitative data-to shed light on the pathways by which health and social disparities can be reduced, as well as to illuminate how scientific research can inform policy development for neighborhood-focused health improvement. CPIC is a community-partnered randomized trial comparing the effectiveness of a community engagement and planning (CEP) intervention that activates multi-agency networks versus a technical assistance model for individual agencies, in implementing evidence-based interventions for depression in two under-resourced communities of color in Los Angeles. Analyses of 6-month client outcomes indicate that the CEP intervention, relative to technical assistance, led to improved mental wellness and physical health and reduced prevalence of poor mental health, risk factors for homelessness, and missed work days due to health. CPIC was implemented with community participatory co-leadership, including leaders' self-reflection on racism and social justice. The proposed investigators are original developers of CPIC. The proposed new secondary analyses and new qualitative data collection will clarify pathways for intervention effects on key subgroups (each community, African Americans and Latinos, men and women, homeless); develop explanatory models using mixed-methods; document intervention implementation for these groups; and explore the applicability and generalizability of the CPIC approach for a new Los Angeles County neighborhood-based health improvement initiative. The public health significance of the research is enhanced by the fact that it will be conducted entirely in partnership with leaders and members from the affected communities using a Community Partnered Participatory Research approach, which promotes equality and collaborative responsibility for all phases of work. Through that model's focus on equity and self-reflection among all leaders on the impact of racism, the proposed project will serve as an early example of a fourth-generation approach to addressing health disparities, which combines comprehensive intervention models and research strategy that incorporates the community context for racial and ethnic differences and the interactions in partnered leadership. .